Can You Take Expired Mucinex?

In our latest question and answer, the pharmacist discusses whether or not expired Mucinex (guaifenesin) is safe to take.

Jan 23, 2018

Ashley asked

Can you take expired Mucinex (guaifenesin)?


In most cases, it is not recommended to take expired Mucinex as it may not be as potent as it once was when it was in date. It is important to note this applies to all Mucinex products such as:

  • Mucinex
  • Mucinex Maximum Strength
  • Mucinex DM
  • Mucinex Fast Max
  • Mucinex D
  • Mucinex Sinus

In fact, it is not recommended to take any medication that is past the expiration date.

Expired Mucinex May Have A Loss Of Potency

As stated, the reason that it not recommended to take expired Mucinex (and other medication) is that it may not be as potent as it once was when it was in-date. Medications are less stable over time and tend to break down. This is especially true if they have been exposed to light, moisture, heat or other factors that could accelerate decomposition.

Although expired medications are more likely than non-expired medications to be less potent, it is often difficult to tell whether or not they have broken down simply by looking at the medication. Very few medications will exhibit tell-tale signs that they have gone "bad". One example in which breakdown is obvious is aspirin. Aspirin has a characteristic smell once it begins to chemically degrade. Mucinex however, tends not to have any noticeable indicators.

You may be wondering how expiration dates are set for products like Mucinex. Manufacturers will perform stability tests on their product for a finite period of time, usually two to three years. After this time, there is no data to go on in regard to determining whether a medication is still as stable and potent as labeled. In other words, the expiration is marked for however long the manufacturer has stability data for.

Interestingly, data from various studies indicate that it takes most medication quite a long time to lose a significant percentage of their original potency. One study, conducted in the 1980's, found that many medications retained about 70-80% of their original potency after 10 years when stored in the original container! The issue is, there is no definitive way to tell without testing.

Is Expired Mucinex Safe To Take?

It is very possible that Mucinex may still be good and have the expected benefit once it is expired, but again, there is no data to confirm this. Theoretically, manufacturers could perform stability tests for longer periods of time, but there generally isn't any financial incentive to do so. In addition, set expiration dates ensure that products need to be repurchased by a retailer/wholesaler once existing products expire.

The good news is that there are no reports of expired Mucinex products causing harm to anyone as Mucinex doesn't break down into harmful components. The main concern is that expired Mucinex simply may not work as well as in-date products. As Mucinex is available over the counter and is relatively inexpensive, it makes sense to buy a new, replacement product to ensure potency.

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